Fishery bulletin of the Fish and Wildlife Service - NOAA

272 SALMON OF THE KAKLUK EIVER, ALASKA
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О 20 40 60 80 100
PERCENTAGE OF FOUR-FRESH-WATER FISH IN ESCAPEMENT
FIGU&E 9.—Percentage of four-fresh-water flsh in return plotted against percentage of four-fresh-water fish in escapement for the
years 1922 and 1924 to 1929, inclusive. The straight line represents a ratio of 1 to 1.
SEAWARD MIGRATIONS
The seaward migration of Karluk River red salmon takes place during the last
week of May and the first 2 weeks of June each year. A few fish migrate sometimes
a day or two earlier or later than this period but the major part of the migration, and
frequently the entire migration, takes place during these 3 weeks. During the migration
period the seaward migrants can be observed in front of the counting weir where
they congregate in schools of a few hundred to tens of thousands. Only occasionally
can they be seen going through the weir during the daytime, but just at dusk the
schools above the weir drop downstream and begin to pass through the spaces between
the pickets. Where there is any appreciable current, the fish always head upstream
even when migrating downstream. Seaward migrants are present in the river above
the weir for only 10 to 16 days each year, although the migration period may extend
over a period of 3 weeks. They may be quite abundant one day, entirely absent the
next, and present again the following day.
The percentage occurrence of the various age groups in the random samples of
seaward migrants collected at the weir site is presented in table 26. Samples were not
collected every day that migrants were present in the river, but since 1930 samples
have been taken every day that fish were abundant.
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